The invention relates generally to filament mowers, i.e., to mowers which cut grass and vegetation by means of a rotating flexible filament string extending from a filament head. In particular, the invention relates to arrangements in a filament mower for selectively advancing filament string from the head.
Attention is directed to the hand held filament trimmers disclosed in the U.S. Purdue Pat. No. 4,134,204 issued Jan. 16, 1979, and in the Ballas U.S. Pat. Nos. 4,177,561 issued Dec. 19, 1979, 4,162,575 issued July 31, 1979 and 4,172,322 issued Dec. 30, 1979, all of which disclose a filament head which includes an arrangement operable in response to activation from above for selectively advancing filament from the head.
Attention is further directed to the hand held filament trimmer disclosed in the Proulx U.S. Pat. No. 4,097,991 issued July 4, 1978.
Attention is also directed to the filament mower disclosed in the Pittinger U.S. Pat. No. 4,077,191 issued Mar. 7, 1978.
Attention is also directed to the U.S. Pittinger Pat. No. 4,189,830 issued Feb. 26, 1980 which discloses a filament head.
Attention is also directed to one prior commercial hand held "bump head" filament trimmer which included a downwardly open spool cover which was fixed to the handle against axial movement and which was rotatably driven by a prime mover, and a spool which was carried for rotary movement relative to the spool cover and for axial movement relative to the spool cover between upper and lower positions, together with means on the spool and on the spool cover for interengaging the spool cover and the spool for common rotation when the spool was in the upper position and in the lower position and for permitting limited relative rotation between the spool and the spool cover during movement of the spool between the upper and lower positions, and means biasing the spool away from the spool cover and toward the lower position. In operation of this filament trimmer, filament string was played out in response to manual "bumping" of the bottom of the spool against the ground to effect axial movement of the spool relative to the spool cover and thereby to selectively play out the filament string from the filament head.